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Central corneal thickness: will one measurement suffice?
Louisa Wickham1, Beth Edmunds, Ian E Murdoch
1Moorfields Eye Hospital, London, United Kingdom. louisa.w@tiscali.co.uk
Ophthalmology
|February 5, 2005
Summary
Central corneal thickness (CCT) measurements in glaucoma patients show significant variability over three months. Multiple CCT readings are crucial for accurate glaucoma risk assessment and to avoid patient misclassification.
Area of Science:
- Ophthalmology
- Glaucoma Research
- Corneal Physiology
Background:
- Central corneal thickness (CCT) is a key factor in glaucoma risk assessment.
- The Ocular Hypertension Treatment Study (OHTS) established criteria for glaucoma risk based on CCT.
- Variability in CCT measurements could impact risk stratification.
Purpose of the Study:
- To evaluate the measurement of central corneal thickness (CCT) in glaucoma patients over a 3-month period.
- To assess the impact of CCT variability on glaucoma risk categorization using OHTS criteria.
Main Methods:
- A cohort study design was employed.
- Fifty-one glaucoma patients were recruited from a specialized eye hospital.
- Central corneal thickness was measured using an ultrasonic handheld pachymeter by a trained observer at two consecutive visits.
Main Results:
- Significant fluctuations in CCT were observed over the 3-month period.
- A systematic bias towards increased corneal thickness was noted at the second reading (P = 0.02 for right eye, P = 0.0003 for left eye).
- Applying OHTS criteria to the second reading resulted in 32% of eyes requiring recategorization.
Conclusions:
- Clinical CCT measurements by trained observers can exhibit significant variability.
- Multiple CCT readings are necessary for accurate glaucoma risk assessment.
- Failure to obtain multiple readings may lead to misclassification and inaccurate risk assignment.